Network fluctuations? Oh. yeah!
Same stuff here in Pittsburgh, PA. Network goes back and forth from 0-4 bars a lot on some days, even when I'm just standing in the same spot. When network is iffy, battery life is completely sucky. When network is stable, battery lasts almost all day with normal use, i.e., HEAVY.
Network strength can change anytime, while idle, driving, downloading, on a call, whatever; but I don't have to be doing anything or even moving for it to drop.
When I have 4 bars, phone is great, battery life fine. Less than 4, not so much...
At least my random reboots appear to have stopped.............
Unrooted X, OTA GB.